Stdlib: sprintf() missing %F conversion specifier (should match Zend)

[PurHur]

Category

stdlib · php-src-strict

Problem

Zend supports %F in sprintf() / printf() / vsprintf() as a float conversion alias (uppercase f — same semantics as %f in practice for normal values).

This compiler throws at format-parse time:

LogicException: sprintf() unsupported conversion specifier %F in this compiler build

which breaks real-world format strings and parity with php-src.

php-src reference

• php/php-src ext/standard/sprintf.c — format parser
• php/php-src ext/standard/formatted_print.c — php_sprintf_internal, specifier dispatch (F handled alongside f)
• Stubs: ext/standard/basic_functions.stub.php — sprintf, vsprintf, printf

Repro

# Zend reference
php -r 'echo sprintf("%F\n", 1.2);'

# VM failure today
./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php -r "echo sprintf(\"%F\\n\", 1.2);" 2>&1
php bin/vm.php -r "echo vsprintf(\"%F\\n\", [1.2]);" 2>&1
'

Zend expected: 1.200000 (representative; verify INF/NAN/-0.0 against Zend)
VM today: fatal LogicException before formatting.

Scope (this repo)

Path	Role
ext/standard/VmSprintf.php	add %F branch (likely alias to %f path)
ext/standard/sprintf.php, printf.php, vsprintf.php	entry points
lib/JIT/Builtin/StringFormatJit.php	if JIT parses specifiers separately, add %F there too
lib/JIT/Builtin/SscanfJit.php	out of scope unless scanf gains F (not in php-src)

PHP-in-PHP first — implement in ext/standard + JIT PHP helpers; no runtime/*.c.

Done when

• %F works on VM for sprintf / vsprintf / printf and matches Zend for: normal float, INF, NAN, -0.0
• Unknown specifiers still raise ValueError: Unknown format specifier like Zend (not LogicException)
• test/compliance/cases/stdlib/sprintf_F_specifier.phpt green
• JIT/AOT format JIT path (if enabled) shares VmSprintf logic or documents VM-only gap

Related

• Stdlib: vsprintf() rejects inline array literal — LogicException not formatted string (ext/standard/sprintf.c) #9602 (vsprintf array literal) · Stdlib: sscanf() %* assignment-suppression conversion unsupported — ValueError (ext/standard/formatted_io.c) #9560 (sscanf %*) · Epic: Self-host critical path — compiler compiles itself (M3→M5) #1492

[PurHur]

claim: PHP Compiler STD Lib — starting this run (%F in sprintf/printf/vsprintf; VM + AOT verification).

[PurHur]

claim: worker-lane-B — starting this run

[PurHur]

Merged via PR #10745.

Fix: %F routes through the same float formatting path as %f in VmSprintf and StringFormatJit.

Verification:

./script/docker-exec.sh -- bash -lc 'source script/php-env.sh
php bin/vm.php -r "echo sprintf(\"%F\n\", 1.2);"
./vendor/bin/phpunit --filter sprintf_F_specifier
'

→ 1.200000 and OK (4 tests, 4 assertions) (VM + JIT compliance guards).